In wireless communication networks, there are communication nodes, for example microwave link nodes. Microwave link nodes normally comprise microwave link antenna devices, where a microwave link antenna arrangement normally is connected to a radio branch for transmission, a transmission branch, via the antenna device, and a radio branch for reception, a reception branch, via the antenna device.
A microwave link antenna device is usually connected to a transmission branch and a reception branch via a diplexer arrangement that comprises a first band-pass filter that is connected to the reception branch and a second band-pass filter that is connected to the transmission branch. A three-port junction connects the transmit and receive branches to the antenna device.
Such a diplexer is relatively expensive to manufacture, and constitutes a quite space-consuming component. Furthermore, microwave links are manufactured and sold for many different frequency bands, and it is necessary to have one specific diplexer per frequency band, due to the frequency dependency of components.
There is thus a need for a less complicated and more compact diplexer arrangement and radio system, in particular regarding a transition between, on one hand, a transmission branch and a reception branch, and, on the other hand, an antenna device.